Bomosa Looks Inwards, Turns Attention To Local Sources Of Feeds

05 October 2009   |   11:37 pm  

 In their work on efficacy of Boiled Tea Leaf Meal (BLTM) in diets for Oreochromis niloticus(L) (Tilapia) and its effects on the liver and whole body composition, involving David Liti, Herwig Waidbacher and five others, leaves plucked from the tea Camellia sinensis (L). plant, used for making the most consumed beverage in the world, were used experimentally.


The tea leaves residues thrown away as wastes, after preparation of tea as a beverage, were considered a possible candidate for raw material for feeding fish. Their consideration was that, with the high tea production in Kenya and with most of the tea residues being thrown away as waste, it was logical to tap into using the residues as fish feed.

Their broad objective was to develop “a cheap and effective diet for O.. niloticus culture by evaluating the efficacy of BTLM as a substitute for freshwater shrimp meal (FSM) in the conventional fish diet. Specific objectives also were aimed at: evaluating the effect of BTLM as a possible replacement for the fresh water shrimp meal in the conventional diet on the growth and performance; determining the appropriate replacement level of the FSM ingredient in the conventional (control) diet with BTLM; and determining the consequences of increasing dietary inclusion of the plant ingredients on the whole body proximate composition and hepatosomatic index (HSI) of the experimental fish.

Although the proximate analysis results showed BTLM to have higher CP values of 27 per cent, and analyses indicated that BTLM wastes can be used to substitute freshwater shrimp meal from diets used to culture O. niloticus, it nonetheless suffered a serious setback due to certain reasons. In a feeding experiment lasting 60 days, an increase in dietary inclusion of BTLM up to 50 per cent had no significant effect on the fish growth performance in hapas. Feeding O. niloticus on increasing levels of BTLM resulted in poor growth performance in aquaria. Fish exhibited significant decrease in some critical physiological parameters in values. Their verdict from findings was that “it was impossible to replace FSM with BTLM beyond zero per cent in aquaria.”

Their ‘possible reasons for poor growth’ were identified as: growth inhibitors, deficiency in one or more amino acids, trypsin inhibitors, amylase inhibitor, presesence of phytic acid or presence of high dietary crude fibre content.

The same group of seven scientists also ventured into investigating the efficacy of selected plant ingredients as substitutes for Freshwater shrimps Caridina niloticus in diets for Nile tilapia Oreochromis niloticus(L), using local plants and crop parts not normally eaten by man. They worked on quality, proximate composition and effect of selected plant ingredients on growth performance and effect on whole body proximate composition. They wanted to develop cheap and effective diets for O. niloticus culture by evaluating the effectiveness of selected plant materials as substitutes for freshwater shrimp meal, in the conventional fish diet.

They selected Pawpaw Leaf Meal (PLM), Cassava Leaf Meal (CLM) and Boiled Tea Leaf Meal (BTLM) as possible replacement for the fresh water shrimp meal in the conventional diet on the growth and performance. Their conclusion was that cassava leaves replace up to 50 per cent freshwater shrimps from diets used to culture O. niloticus in earthen ponds. They indicated that, “in glass aquaria or recirculating systems like concrete tanks, cassava leaves can only replace up to 25 per cent of the freshwater shrimp meal.”

“At 100 per cent BTLM replacement, the fish could still grow, but would take more time to reach market sizes. At 100 per cent BTLM, the diet would play a more important role of fertilising the pond than as a fish feed,” they observed. They added, however, that pawpaw leaves can successfully replace up to 100 per cent of freshwater shrimp meal from diets used to culture O. niloticus in recirculating tanks and in earthen ponds.

They pointed out that the combination of pawpaw leaves, cotton seed cake, wheat bran and freshwater shrimp meal improved the diet and enhanced growth, saying “pawpaw leaves may have improved the nutritive values of the diets.” They emphasised that the results of the study, using pawpaw leaves, can be used as a benchmark for further research. They drew attention to the fact that alternative processing of the pawpaw or cassava leaves prior to use could be done to determine if the ingredients will have a better effect on O. niloticus growth. According to them, the study also recommends fermentation of cassava leaves to decrease cyanide content.

Moi University, KMFRI, BOKU University, DFK Sagana, EIAR-Ethiopia and DFRU-Uganda partnered in a work to develop optimised feed processing and dispensing devices, using appropriate technologies. They compared feed processing equipment at Sagana Aquaculture Centre before EU Bomosa project and after. According to them, feed production capacity per day entailed two 70kg bags per day before, while feed processing equipment advanced during EU Bomosa project, leading to feed production capacity of five 70kg bags per day. They said the difference was due to increased production capacity. Advancement in feed storage was also identified as increasing from feed storage shelf life of three months (before Bomosa) over six months after.

They sought solution to hand feeding, using simple, locally fabricated, automated feeders. Their achievements were listed as: increased feed production capacity, improved fish growth performance (275g/6 months) and improved feed conversion rate (FCR).

Matthew Mwanja, Wilson Mwanja, Jonathan Munguti, Peter Akoll and Andrew Bende in their own report provided an insight into feeds development for BOMOSA cage farming System in Uganda. In their work, in which they tried two different diets, they concluded that several low or none value ingredients exist locally. They posited that fish farmed in cages in small water reservoirs grows to table size and feed making technology is easy to adopt and transfer. According to them, further formulation to cover other ingredients and improvement in processing is needed and diets should be tried out for other fish species found in the plot areas. They recommended that research should continue on varied fish regimes to attain faster fish growth rates.

On Bomosa approach to fish feeding, it was acknowledged that fish feed contribute to over 45 per cent of total operational cost in fish farming ventures, but that Bomosa technology utilises locally available feeds ingredients in fish feed formulation in order to cut down on costs and for sustainability.

Waidbacher, Munguti and two others did a review on locally available feedstuffs for aquaculture development in Ethiopia, indicating that “the nutrient content of crop residue were found to be very low, but currently in the highlands more and more land is being cultivated for crop production to satisfy the increasing human demand for food.. Consequently, crop residues remain the main livestock and fish feed source thus emphasis should be given to assess possibilities for more use of crop residues and improving nutritional value.”

The Liti, Waidbacher, Mbaluka team of seven whose work had been alluded to earlier had much more to say. “In Kenya cassava is mainly used for human food although there is also limited use as animal feeds. The choice of cassava for use in O. niloticus diets was based on its availability and crude protein content values.” On these bases, they sought to develop a cheap and effective diet for O. niloticus culture by evaluating the efficacy of Cassava Leaf Meal (CLM) as a substitute for freshwater shrimp meal (FSM) in the conventional fish diet.

They attempted to determine the appropriate replacement level of the FSM ingredient in the conventional (control) diet with CLM, and the consequences of increasing dietary inclusion of the plant ingredients on the whole body proximate composition and hepatosomatic index (HSI) of the experimental fish. Their results from the study showed that cassava leaves can replace up to 50 per cent of FSM from diets formulated for the culture of O. niloticus in earthen ponds or semi intensive culture and, at 100 per cent CLM there was slowed growth and low final body weights.

Their explanations: Possible reasons to for low growth rates include diet unpalatability, ANFs and high crude fibre content. Leaves are known to contain tannins that give a bitter taste. Cassava leaves have linamarin, a toxic compound that causes cyanide poisoning. The toxic effect can be removed by boiling or sun drying. Before the cassava leaves were incorporated into the diets they were sun-dried as a processing precaution to reduce toxicity. Fermentation of cassava leaves could reduce the cyanide levels. Alkaline fermentation of cassava leaves is done in Congo to produce ‘Ntoba mbodi’. Decrease in cyanide content is due to hydrolysis of cyonogenic glucosides (linamarin) by bacteria produced linamarase

On the Potential of pawpaw leaf meal to replace Freshwater shrimps Caridinia niloticus in diets for Nile tilapia Oreochromis niloticus (L), the same group of seven stated that Plant sources are promising alternatives and legumes are both naturally abundant and high in protein content.

They sought to To develop a cheap and effective diet for O. niloticus culture by evaluating effectiveness of selected Paw Leaf Meal (PLM) as a substitute for freshwater shrimp meal (FSM) in the conventional fish diet. The study concluded that pawpaw leaves can successfully replace up to 100 per cent of freshwater shrimp meal from diets used to culture O. niloticus in recirculating tanks and in earthen ponds. Fish fed on 25 per cent and 50 per cent PLM had better mean average weights compared to the control diet. Pawpaw leaves may have improved the nutritive value of the diets. They inferred that pawpaw leaves therefore have a great potential to be included in diets used to culture the Nile tilapia Oreochromis niloticus in fertilized earthen ponds

Partner Institutes that worked on nutritive content of selected potential feed ingredients for inclusion in fish feeds in Kenya, Uganda and Ethiopia (KMFRI, MU, BOKU, DFK, EIAR and DFRU) showed some distinctive features. Working closely with partners in the three countries. They embarked on on-field in the tours in the three countries, collecting samples, processing the samples in the for proximate analysis and diet formulations. Remarkably, there was high contribution from students- undergraduate, MSc and PhD working with students. A total of 48, 14 and 16 feedstuffs were analysed in Kenya, Uganda and Ethiopia respectively..

They considered catfish and tilapia remains, poultry feathers, freshwater shrimps and Omena fish as animal sources, while looking at leaves of banana, papaya, cassava, arrowroot, sweet potato, seed meals of cotton, sunflower, mango, papaya, Cereal bran of maize, wheat and rice; and seed husks of coffee and cotton as plant sources.

From Kenya, they identified cereal brans, freshwater shrimps, Omena fish, hydrolysed feather meal, Mexican sunflower, Galisonga Persiflora, lucerne seed, sesbania seed, French bean, tomato peels, onion leaves, avocado leaf and brewers’ yeast. From Ethiopia, however, catfish and tilapia fillet remains, Garra fish spp, sorghum beetle, Lathyrus pea (Vetch) coat, beans coat, peas coat, lentil pod, brewery by-products, tuffs remains,flour mill leftover – (Teragi), cotton seed cake and wheat bran came handy.

For Uganda, brans of maize and rice, seed cake of cotton seed and sunflower, fishmeal – Mukene, Lates niloticus skeleton, freshwater shrimps, leaves of cassava, sweet potatoes, papaya peas, beans, arrowroot, Mexican sunflower, Omenta, off cuts of potato and banana peels, local brew (malwa) dregs, chicken offals, and slaughter house waste, Kitchen left overs were considered.

Rosemary Nalwanga from Kyambogo University, Kampala-Uganda, presented her work on the quality of fish feed ingredients and the challenges to the development of cage culture of Nile tilapia (O.niloticus) in Eastern Africa. The peculiar problems, according to her, were: Lack of information on the nutritional quality and costs of nutrients of locally available feed ingredients from different sources and outlets as well as absence of information on nutrient composition and costs of commercial feeds.

The summary of her findings was that fish resources (fish meal) most adulterated, followed by oil cakes; adulteration depends on market prices; shops are the most expensive yet with the most sub-standard ingredients; the quality of commercial feeds is compromised. Implications, according to her, were poor growth of fish and poor profitability. These, she said, threaten the environment as fish feed ingredients are highly adulterated with mainly sand and this hampers aquaculture development. Moreover, “the quality of feeds needs to be improved with care in sourcing of ingredients in order to have economically feasible and sustainably growing aquaculture.”

She recommended that feed mills and farmers should source their ingredients from landing sites or oil factories or milling plants and at least from stores, there is a need for strict quality control policies especially for fish meal, small scale farmers should form co-operatives, there is need for raising awareness for the quality of fish feeds; further work should be directed towards developing indicators which can be used in the field for assessing the quality of ingredients.

Others who jointly worked on nutritional value of selected potential feedstuffs for sustainable aquaculture of Nile tilapia (O. niloticus) acknowledged that aquaculture is mainly a smallholder operation and is frequently integrated with other farming activities. They lamented that there are no established aquafeed industries, that high degree of processing is not suitable and also that there is potential for improved self-sufficiency if unprocessed and low-processed feed components can be utilised. They pointed out that there is a great variety of potential feedstuffs in the region.

Their conclusion was that the non-conventional feedstuffs have good potential, based on nutrient content (proximate analysis), local availability and potential competition with other uses. They complained about the lack of original data for amino acids, substantial variability in nutrient content (locality, strain, site of access in supply chain, etc.) and that acceptability by fish is substantially different for different feed components.

The achievements in feeds within Bomosa project were identified as: Scientific data – through publications, better fish yields, improved feed conversion rates, longer shelf life of formulated feeds, contributions towards protein provision and improved income.

You may also like